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<pre><span class="sourceLineNo">001</span><a name="line.1"></a>
<span class="sourceLineNo">002</span>/*<a name="line.2"></a>
<span class="sourceLineNo">003</span> * Copyright (C) 2014 Archie L. Cobbs. All rights reserved.<a name="line.3"></a>
<span class="sourceLineNo">004</span> *<a name="line.4"></a>
<span class="sourceLineNo">005</span> * $Id: GeneratedIdCache.html 842 2015-03-07 18:20:42Z archie.cobbs $<a name="line.5"></a>
<span class="sourceLineNo">006</span> */<a name="line.6"></a>
<span class="sourceLineNo">007</span><a name="line.7"></a>
<span class="sourceLineNo">008</span>package org.jsimpledb.util;<a name="line.8"></a>
<span class="sourceLineNo">009</span><a name="line.9"></a>
<span class="sourceLineNo">010</span>import java.util.HashMap;<a name="line.10"></a>
<span class="sourceLineNo">011</span><a name="line.11"></a>
<span class="sourceLineNo">012</span>import org.jsimpledb.core.ObjId;<a name="line.12"></a>
<span class="sourceLineNo">013</span>import org.jsimpledb.core.Transaction;<a name="line.13"></a>
<span class="sourceLineNo">014</span><a name="line.14"></a>
<span class="sourceLineNo">015</span>/**<a name="line.15"></a>
<span class="sourceLineNo">016</span> * Cache for randomly generated object IDs based on unique strings.<a name="line.16"></a>
<span class="sourceLineNo">017</span> *<a name="line.17"></a>
<span class="sourceLineNo">018</span> * &lt;p&gt;<a name="line.18"></a>
<span class="sourceLineNo">019</span> * Instances are thread safe.<a name="line.19"></a>
<span class="sourceLineNo">020</span> * &lt;/p&gt;<a name="line.20"></a>
<span class="sourceLineNo">021</span> *<a name="line.21"></a>
<span class="sourceLineNo">022</span> * @see XMLObjectSerializer<a name="line.22"></a>
<span class="sourceLineNo">023</span> */<a name="line.23"></a>
<span class="sourceLineNo">024</span>public class GeneratedIdCache {<a name="line.24"></a>
<span class="sourceLineNo">025</span><a name="line.25"></a>
<span class="sourceLineNo">026</span>    private final HashMap&lt;String, ObjId&gt; map = new HashMap&lt;&gt;();<a name="line.26"></a>
<span class="sourceLineNo">027</span><a name="line.27"></a>
<span class="sourceLineNo">028</span>    /**<a name="line.28"></a>
<span class="sourceLineNo">029</span>     * Generate an object ID for the given object type storage ID and string.<a name="line.29"></a>
<span class="sourceLineNo">030</span>     *<a name="line.30"></a>
<span class="sourceLineNo">031</span>     * &lt;p&gt;<a name="line.31"></a>
<span class="sourceLineNo">032</span>     * If an {@link ObjId} has already been created for the specified {@code storageId} and {@code string} by this instance,<a name="line.32"></a>
<span class="sourceLineNo">033</span>     * it will be returned.<a name="line.33"></a>
<span class="sourceLineNo">034</span>     * Otherwise, a random {@link ObjId} for which no object exists in the specified {@link Transaction} is generated<a name="line.34"></a>
<span class="sourceLineNo">035</span>     * and returned.<a name="line.35"></a>
<span class="sourceLineNo">036</span>     * &lt;/p&gt;<a name="line.36"></a>
<span class="sourceLineNo">037</span>     *<a name="line.37"></a>
<span class="sourceLineNo">038</span>     * @param tx transaction from which to allocate new object IDs<a name="line.38"></a>
<span class="sourceLineNo">039</span>     * @param storageId object type storage ID<a name="line.39"></a>
<span class="sourceLineNo">040</span>     * @param string unique string<a name="line.40"></a>
<span class="sourceLineNo">041</span>     * @return unique, unallocated object ID corresponding to {@code storageId} and {@code string}<a name="line.41"></a>
<span class="sourceLineNo">042</span>     * @throws IllegalArgumentException if {@code storageId} is invalid<a name="line.42"></a>
<span class="sourceLineNo">043</span>     * @throws IllegalArgumentException if {@code tx} or {@code string} is null<a name="line.43"></a>
<span class="sourceLineNo">044</span>     */<a name="line.44"></a>
<span class="sourceLineNo">045</span>    public synchronized ObjId getGeneratedId(Transaction tx, int storageId, String string) {<a name="line.45"></a>
<span class="sourceLineNo">046</span>        if (tx == null)<a name="line.46"></a>
<span class="sourceLineNo">047</span>            throw new IllegalArgumentException("null tx");<a name="line.47"></a>
<span class="sourceLineNo">048</span>        if (string == null)<a name="line.48"></a>
<span class="sourceLineNo">049</span>            throw new IllegalArgumentException("null string");<a name="line.49"></a>
<span class="sourceLineNo">050</span>        final String key = "" + storageId + ":" + string;<a name="line.50"></a>
<span class="sourceLineNo">051</span>        ObjId id = this.map.get(key);<a name="line.51"></a>
<span class="sourceLineNo">052</span>        if (id == null) {<a name="line.52"></a>
<span class="sourceLineNo">053</span>            id = tx.generateId(storageId);<a name="line.53"></a>
<span class="sourceLineNo">054</span>            this.map.put(key, id);<a name="line.54"></a>
<span class="sourceLineNo">055</span>        }<a name="line.55"></a>
<span class="sourceLineNo">056</span>        return id;<a name="line.56"></a>
<span class="sourceLineNo">057</span>    }<a name="line.57"></a>
<span class="sourceLineNo">058</span><a name="line.58"></a>
<span class="sourceLineNo">059</span>    /**<a name="line.59"></a>
<span class="sourceLineNo">060</span>     * Clear this instance.<a name="line.60"></a>
<span class="sourceLineNo">061</span>     */<a name="line.61"></a>
<span class="sourceLineNo">062</span>    public synchronized void clear() {<a name="line.62"></a>
<span class="sourceLineNo">063</span>        this.map.clear();<a name="line.63"></a>
<span class="sourceLineNo">064</span>    }<a name="line.64"></a>
<span class="sourceLineNo">065</span>}<a name="line.65"></a>
<span class="sourceLineNo">066</span><a name="line.66"></a>




























































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